The present invention generally relates to fuel-fired heating appliances and, in a representatively illustrated embodiment thereof, more particularly relates to a fuel-fired direct vent water heater having a specially designed sealed combustion chamber assembly incorporated therein.
Modern fuel-fired direct vent water heaters are commonly provided with a “sealed” combustion chamber. In this context, the term “sealed” means that the water heater combustion chamber does not exceed the internal pressure-created leakage test flow rates set forth in section 2.33.3 of the American National Standard/CSA Standard for Storage Water Heaters With Input Ratings of 75,000 Btu Per Hour or Less.
While this sealed combustion chamber design provides the direct vent water heater with a variety of operational advantages, including facilitating a flammable vapor ignition resistant design of the water heater, it also tends to introduce a variety of undesirable operational characteristics including diminished ignition performance leading to sooting in the combustion chamber, decreases in burner flame stability, increased NOx emissions and a lessening in combustion performance. It would thus be desirable to provide a combustion chamber assembly for a fuel-fired heating appliance, such as a water heater, in which these potential design problems are eliminated or at least substantially diminished.